There's a Gears of War Board Game

Epic Games' popular shooter franchise is now a board game. You and up to three other friends can take on Locust hordes through seven, randomly generated missions. Players use special 'Order' cards on his or her turn to take cover or lay down suppressing fire. The promotional video gives a great overview of the rules. Gears of War: The Board Game will be out later this year.

Fantasy Flight has made a number of board game conversions of popular video games (WoW and Starcraft come to mind). They are absolutely fantastic designers that masterfully capture the essence of the properties they adapt for tabletop. If you like Gears and have a group of people willing to play, go for it.

Also, given that the game has an "AI", this (and so many other of their games) can be played solo.